New research suggests that switching to hydrogen fuel could have some negative near-term effects on the environment. Hydrogen is often touted as the ideal alternative to gasoline-engined vehicles, and manufacturers such as Toyota have spent lots of money and time evaluating the technology. But, as with anything, there's a downside.

In a joint study between Princeton University and the National Oceanic and Atmospheric Association, researchers have found that hydrogen reacts in a unique way with hydroxyl radical (OH), a molecule that is responsible for soaking up greenhouse gases (such as methane) from the atmosphere.

The study found that OH will not be able to serve this crucial purpose once a certain level of hydrogen emissions is reached, which would lead to a worrying amount of methane in the atmosphere, contributing to unexpected environmental issues.

Lead author of the study, postdoctoral researcher Matteo Bertagni, told Sci Tech Daily that these effects would occur even if hydrogen replaced fossil fuels as a common energy source. Furthermore, the risk is heightened by hydrogen production processes that require methane.

Various environmental organizations claim that 20% of global warming effects can be attributed to methane, which reportedly has nearly 80 times the warming power of carbon dioxide. "In practice, though, it poses many environmental and technological concerns that still need to be addressed." Essentially, the study shows that automakers still need to find ways to minimize emissions that result from hydrogen production.

Bertagni added that hydrogen emitted into the atmosphere today would lead to a methane build-up in the coming years. "Even though hydrogen only has a lifespan of around two years in the atmosphere, you'll still have the methane feedback from that hydrogen 30 years from now."

The figures differ slightly depending on the hydrogen production methods. Green hydrogen, which is made by splitting water into hydrogen and oxygen using renewable electricity, has a critical emissions threshold of 9%. If more than that leaks into the atmosphere at any point across the chain, atmospheric methane would increase, wiping away all the benefits associated with moving away from traditional fossil fuels.

For blue hydrogen, which involves methane in the production process, the threshold is even lower. According to the research, leakage would not be able to exceed 4.5% to prevent the increase of methane in the atmosphere. "We have a lot to learn about the consequences of using hydrogen, so the switch to hydrogen, a seemingly clean fuel, doesn't create new environmental challenges," explained Amilcare Porporato.

While hydrogen cars like the Toyota Mirai emit nothing but warm air and water vapor, leaks during transportation and production pose a genuine threat, says the study.

The study isn't against hydrogen as an alternative to traditional ICE-powered vehicles and EVs but notes that more work needs to be done to ensure it truly is a sustainable means of propulsion. "If companies and governments are serious about investing money to develop hydrogen as a resource, they have to make sure they are doing it correctly and efficiently," added Bertagni. "Ultimately, the hydrogen economy has to be built in a way that won't counteract the efforts in other sectors to mitigate carbon emissions."

It seems the perfect solution isn't here yet. Across the world, the combustion engine is slowly being outlawed, with provisions being made for electric vehicles and the like. But even battery-powered cars aren't perfect; they don't emit any harmful local emissions, but manufacturing an EV is a filthy business, with plenty of natural materials required for battery production.

Perhaps synthetic fuels hold the key to future mobility, but even then, there will be emissions, albeit net-zero emissions.